Upgrade SQL Server 7 to SQL Server 2000

Hi, friends
I have writen an application in VB6, that use data from SQL SERVER 7. Now, I upgrade data to SQL SERVER 2000. Then I create another packet for it, and install this packet to my all my client user computer. But my program in client user computer could not connect to SQL SERVER 2000, only be able to connect to SQL SERVER 7.

(This program is still able to connect to SQL 2000 from my programming computer)

Please tell me the way to solve this problem

Thanks,

PNAKiet